As a radiation detector used for CT sensors and others, there is a detector of a configuration wherein, with respect to a semiconductor photodetecting element array such as a photodiode array, a scintillator is installed on a light-incident surface of the photodetecting element array. In the radiation detector of this type, when the radiation such as X-rays, γ-rays, or charged particles, which is an object to be detected, is made incident on the scintillator, the radiation generates scintillation light in the scintillator. Then the semiconductor photodetecting elements detect this scintillation light, thereby detecting the radiation.
With respect to the photodetecting element array, a signal processing element is provided in order to perform signal processing of detected signals outputted from the respective photodetecting elements. In this case, as a configuration for electrically connecting the photodetecting elements to the signal processing element, it is possible to use a configuration for connecting them by various wires, a configuration for connecting them through conduction paths provided in a wiring substrate, and so on (e.g., reference is made to Japanese Patent Application Laid-Open No. 8-330469).